Ambient air temperature can have a significant effect on the performance of pieces of sporting equipment that impart or receive energy transfer through contact with an object, such as another piece of sporting equipment. For example, in northern climates where temperatures are often cool during the early portion of a baseball or a softball season, or during evening games, cool ambient air can reduce the temperature of a softball bat, a baseball bat, a softball, or a baseball, which will have a negative impact on both the longevity and the performance of softball and baseball equipment. In particular, in aluminum bats, denting of the aluminum bats often occurs when temperatures are cool. Moreover, cold bats are more prone to stinging of a user's hands, and cold bats absorb energy as the bat strikes the softball or baseball, thereby negatively impacting the performance of the bat. Similarly, a cool softball or baseball will absorb more energy from the bat contacting the ball as compared to softballs or baseballs having a higher temperature, and thus will travel less distance in cool temperatures.
As another example, cool temperatures can negatively impact the performance of a golf club or a golf ball. During early morning or late evening hours, or generally during the spring or fall in northern climates, the cool air temperature can have a negative impact on the distance a golf ball can be struck due to the cool temperature of the golf club and/or golf ball. With respect to a golf ball, the distance a golf ball will fly and the amount of spin that a golfer can impart to the ball is generally reduced as the temperature of the ball is reduced, because the cool golf ball absorbs more energy than a warm golf ball. With respect to a golf club, again the distance a golf ball will fly and the amount of spin a golfer can impart to the ball is generally reduced as the temperature of the head of the golf club that strikes the ball is reduced.
While attempts have been made to provide warming devices that raise the temperature of certain pieces of sporting equipment, there is a continuing need for improved sporting equipment warming devices. A warming device that is portable and that permits continuous use as the piece of sporting equipment is used is desirable, as is a warming device that utilizes a rechargeable heat source. Moreover, the warmer must be effective, and must be efficient to manufacture and to use.